This invention relates to an electronic pressure sensing device, and more particularly to such a device for use with fluid filters to determine pressure loss across the filter.
Determining the pressure loss across a filter is an every day occurrence and is a very important factor in determining the filter element(s) potential life expectancy and also the costs associated with power consumption.
Mechanical differential pressure gauges and pop-up indicators are offered by most leading filter manufacturers and these generally bolt directly on top of the filter.
A further enhancement of these mechanical devices is to attach a magnet to the moving parts and, at a pre-set differential pressure, have it coincide with an electrical reed switch thus opening up many options for an electrical interface.
A still further enhancement includes a light fitted within the differential gauge casing such that it can send out a visual (flashing) warning when it reaches a pre-set differential pressure.
Even more elaborate designs include differential pressure gauges with built in electronic sensing which can output linear signals (as opposed to a single switch point) which link directly to hand held computers for determining the cost of electrical power consumption against the cost of fitting new filter elements.
The manufacturing market is moving more and more towards computerization, where every aspect of a production line can be controlled via an electronic interface. There are several standard data transfer interfaces such as 4-20 mA (current loop), RS-232 and 485 (serial type) as well as various field bus systems such as Profibus-EMS, Inter-Bus S. and Ethernet. Each of these systems has its own advantages and disadvantages and some operate in a more refined, higher level than others, therefore representing the vast diversity of actual applications. The most common interface used with gauge and differential pressure transmitters is the 4 to 20 ma (current loop) signal.
Unfortunately, the cost of fitting proprietary electronic differential pressure sensors/transmitters is generally very high, not only due to the cost of the sensor/transmitter itself but also due to the cost of associated pipes, fittings, valves, brackets etc. plus the cost of manpower.
This invention addresses the problems concerned with fitting such devices.
According to the present invention there is provided an electronic pressure sensing device comprising a pressure sensing/transmitter module including at least one pressure sensor having a pair of opposed sensing elements, and a pair of inlet ports on the module to supply fluid under pressure to the sensing elements, the device further comprising a plurality of adapters each having a pair of outlet ports for connection to the inlet ports on the module whereby each adapter can be selectively coupled to the module, each adapter being capable of being connected to a different configuration of pressurized fluid supply to feed the associated supply to at least one of the inlet ports on the module, the module further including electronic means for interpreting and transmitting the values of pressures sensed by the sensing elements.
The sensing/transmitter modules may consist of a metal or plastic enclosure containing at least one piezoresistive sensor integrated with and sealed in a fluid tight manner to two sensor manifolds, one to each end of said sensors, which incorporate male connections with captive double O-ring seals which extend from the front of the module and with which pressure tight connections to any of the adapters may be made.
Furthermore, each sensor manifold may be ported (drilled) in various ways to allow the sensing/transmitter module to operate in at least three different measurement formats by allowing the pressure, directed by the adapters from the application, to be directed to the appropriate sensor pressure port.
Said module may contain all the necessary circuitry with which to accept a 12-24 VDC electric power input and to output a current or voltage signal directly proportional to the pressure being measured with an accuracy greater than xc2xd% of the pressure range being measured.
An integrated electrical connector provides means with which to make input and output electrical connections while maintaining an IP65 seal. A yellow LED may extend from the rear of the case to give a positive indication of power supply to the device.